### Breaking Changes:
- OFW: Battery: Rework gauge driver initialization routine (by @skotopes)
  - Reworks how communication with battery guage is done, improves reliability and fixes issues with battery percentage not showing
  - After installing firmware with this change, downgrading to old firmware will cause battery percentage to be blank
  - If you must downgrade firmware, use the [Guage Tool app](https://github.com/skotopes/flipperzero_gauge_tool) to unseal the guage
- OFW: JS: Modules backport & overhaul (by @portasynthinca3), backport of backport (by @Willy-JL & @xMasterX)
  - OFW backported some modules we had, added lots of new stuff, and overhauled many other things
  - Non-exhaustive list of changes to help you fix your scripts:
    - `badusb`:
      - `setup()`: `mfr_name`, `prod_name`, `layout_path` parameters renamed to `mfrName`, `prodName`, `layoutPath`
      - effort required to update old scripts using badusb: very minimal
    - `dialog`:
      - removed, now replaced by `gui/dialog` and `gui/file_picker` (see below)
    - `event_loop`:
      - new module, allows timer functionality, callbacks and event-driven programming, used heavily alongside gpio and gui modules
    - `gpio`:
      - fully overhauled, now you `get()` pin instances and perform actions on them like `.init()`
      - now supports interrupts, callbacks and more cool things
      - effort required to update old scripts using gpio: moderate
    - `gui`:
      - new module, fully overhauled, replaces dialog, keyboard, submenu, textbox modules
      - higher barrier to entry than older modules (requires usage of `event_loop` and `gui.viewDispatcher`), but much more flexible, powerful and easier to extend
      - includes all previously available js gui functionality (except `widget`), and also adds `gui/loading` and `gui/empty_screen` views
      - currently `gui/file_picker` works different than other new view objects, it is a simple `.pickFile()` synchronous function, but this [may change later](https://github.com/flipperdevices/flipperzero-firmware/pull/3961#discussion_r1805579153)
      - effort required to update old scripts using gui: extensive
    - `keyboard`:
      - removed, now replaced by `gui/text_input` and `gui/byte_input` (see above)
    - `storage`:
      - fully overhauled, now you `openFile()`s and perform actions on them like `.read()`
      - now supports many more operations including different open modes, directories and much more
      - `virtualInit()`, `virtualMount()`, `virtualQuit()` still work the same
      - effort required to update old scripts using storage: moderate
    - `submenu`:
      - removed, now replaced by `gui/submenu` (see above)
    - `textbox`:
      - removed, now replace by `gui/text_box` (see above)
    - `widget`:
      - only gui functionality not ported to new gui module, remains unchanged for now but likely to be ported later on
    - globals:
      - `__filepath` and `__dirpath` renamed to `__filename` and `__dirname` like in nodejs
      - `to_string()` renamed and moved to number class as `n.toString()`, now supports optional base parameter
      - `to_hex_string()` removed, now use `n.toString(16)`
      - `parse_int()` renamed to `parseInt()`, now supports optional base parameter
      - `to_upper_case()` and `to_lower_case()` renamed and moved to string class as `s.toUpperCase()` and `s.toLowerCase()`
      - effort required to update old scripts using these: minimal
  - Added type definitions (typescript files for type checking in IDE, Flipper does not run typescript)
  - Documentation is incomplete and deprecated, from now on you should refer to type definitions (`applications/system/js_app/types`), those will always be correct
  - Type definitions for extra modules we have that OFW doesn't will come later

### Added:
- Apps:
  - NFC: Cyborg Detector (by @RocketGod-git)
  - Sub-GHz: Radio Scanner (by @RocketGod-git)
  - Games: Umpire Indicator (by @RocketGod-git)
- Sub-GHz:
  - Show satellites count with an icon (#215 by @m7i-org)
  - Add Bresser 3CH weather station protocol (#217 #245 by @m7i-org)
  - Add Vauno-EN8822 weather station protocol (#262 by @m7i-org)
  - UL: Add Marantec24 protocol (static 24 bit) with add manually (by @xMasterX)
  - UL: Add GangQi protocol (static 34 bit) with button parsing and add manually (by @xMasterX & @Skorpionm)
  - UL: Add Hollarm protocol (static 42 bit) with button parsing and add manually (by @xMasterX & @Skorpionm)
  - UL: Add Hay21 protocol (dynamic 21 bit) with button parsing (by @xMasterX)
  - UL: Add Keeloq Monarch full support, with add manually (by anonymous UL contributor)
  - UL: Princeton custom buttons support (by @xMasterX)
- NFC:
  - OFW: MIFARE Classic Key Recovery Improvements (PR 3822 by @noproto)
    - Accelerated dictionary attack: dictionary attacks reduced to several seconds - checks ~3500 keys per second
    - Nested attack support: collects nested nonces to be cracked by MFKey, no longer requiring Flipper Nested app
    - Static encrypted backdoor support: collects static encrypted nonces to be cracked by MFKey using NXP/Fudan backdoor, allowing key recovery of all non-hardened MIFARE Classic tags on-device
  - Add SmartRider Parser (#203 by @jaylikesbunda)
  - Add API to enforce ISO15693 mode (#225 by @aaronjamt)
  - OFW: H World Hotel Chain Room Key Parser and MFC keys (by @zinongli)
  - OFW: Parser for Tianjin Railway Transit (by @zinongli)
- Infrared:
  - Bluray/DVD Universal Remote (#250 #264 by @jaylikesbunda)
  - Option to "Load from Library File" for Universal Remotes (#255 by @zxkmm)
- Updater: New Yappy themed icon while updating (#253 by @the1anonlypr3 & @Kuronons & @nescap)
- JS:
  - New `i2c` module (#259 by @jamisonderek)
- BadKB:
  - OFW: Add linux/gnome badusb demo files (by @thomasnemer)
  - Add older qFlipper install demos for windows and macos (by @DXVVAY & @grugnoymeme)
  - OFW: New layout for es-LA (by @IRecabarren)
- OFW: Dolphin: Happy mode in Desktop settings (by @portasynthinca3)
- OFW: CLI: Improvements part I, `neofetch` command (by @portasynthinca3), fix for lab.flipper.net (by @xMasterX)
- GUI:
  - OFW: Add up and down button drawing functions to GUI elements (by @DerSkythe)
  - OFW: Extended icon draw function in Canvas (by @RebornedBrain)
- OFW: RPC: Support 5V on GPIO control for ext. modules (by @gsurkov)
- OFW: Toolbox: Proper integer parsing library `strint` (by @portasynthinca3)
- OFW: Furi: Put errno into TCB (by @portasynthinca3)

### Updated:
- Apps:
  - MFKey: Added Static Encrypted Nested key recovery, Added NFC app support, Dropped FlipperNested support (by @noproto)
  - WAV Player: Better fix for unresponsiveness, handle thread exit signal (by @CookiePLMonster)
  - Laser Tag: External Infrared board support, crash fixes (by @RocketGod-git), RFID support for ammo reload, thread leak fix (by @jamisonderek)
  - ESP Flasher: Update blackmagic bin with WiFi Logs (by @DrZlo13), support more board types (by @xMasterX)
  - Picopass: File loading improvements and fixes (by @bettse), force ISO15693 1OutOf4 mode (by @aaronjamt)
  - Quac!: External IR board support (by @daniilty), import all IR from file, iButton support, code improvements (by @rdefeo)
  - DTMF Dolphin: Add EAS tone support (by @JendrBendr)
  - NFC Playlist: Error screens for playlist already exists and item already in playlist, general improvements (by @acegoal07), refactor rename/new scene without thread (by @Willy-JL)
  - CLI-GUI Bridge: Fixes and improvements (by @ranchordo)
  - Seader: Enable T=1, show error for timeout, fix wrong LRC logging (by @bettse)
  - BLE Spam: Fix menu index callback (by @Willy-JL)
  - Solitaire: App rewrite, Added quick solve, New effects and sounds, Removed hacky canvas manipulation (by @doofy-dev)
  - CLI-GUI Bridge: Add more symbols to keyboard (#222 by @Willy-JL)
  - UL: Sub-GHz Bruteforcer: Add new protocols for existing dump option (by @xMasterX), use FW functions for top buttons (by @DerSkythe)
  - UL: NRF24 Apps: Use string library compatible with OFW SDK (by @xMasterX)
  - OFW: SPI Mem Manager: Fixed UI rendering bug related to line breaks (by @portasynthinca3)
  - OFW: USB/BT Remote: Mouse clicker option to click as fast as possible (by @sumukhj1219)
- CLI: Print plugin name on load fail (by @Willy-JL)
- NFC:
  - Added 6 new Mifare Classic keys from Bulgaria Hotel (#216 by @z3r0l1nk)
  - NDEF parser supports NTAG I2C Plus 1k and 2k chips too (by @RocketGod-git)
  - NDEF parser decodes URL-encoded URI characters (#267 by @jaylikesbunda)
  - UL: Add iq aparts hotel key (by @xMasterX)
  - OFW/UL: Rename 'Detect Reader' to 'Extract MFC Keys' (by @bettse & @xMasterX)
  - OFW: Plantain parser improvements (by @assasinfil)
  - OFW: Moscow social card parser (by @assasinfil)
  - OFW: Fixes and improvements to iso14443_4a listener and poller (by @RebornedBrain)
  - OFW: Update BART station codes in Clipper plugin (by @ted-logan)
- Sub-GHz:
  - UL: Frequency analyzer fixes and improvements (by @xMasterX):
    - Enforce int module (like in OFW) usage due to lack of required hardware on external boards (PathIsolate (+rf switch for multiple paths)) and incorrect usage and/or understanding the purpose of frequency analyzer app by users, it should be used only to get frequency of the remote placed around 1-10cm around flipper's left corner
    - Fix possible GSM mobile towers signal interference by limiting upper frequency to 920mhz max
    - Fix duplicated frequency lists and use user config for nearest frequency selector too
  - Nexus-TH weather station protocol improvements on detection (#256 by @m7i-org)
- Infrared:
  - Additions to MNTM specific LED, Digital Sign, Monitor universal remotes from IRDB (#240 by @jaylikesbunda)
  - UL: Replace LEDs universal remote with new one by Unleashed team, includes color options (by @amec0e & @xMasterX)
  - UL: Update universal remote assets (by @amec0e)
  - OFW: IR button operation fails now shows more informative messages (by @RebornedBrain)
  - OFW: Add Airwell AW-HKD012-N91 to univeral AC remote (by @valeraOlexienko)
  - OFW: Add TCL 75S451 to TV universal remote (by @christhetech131)
  - OFW: Universal remote additions (by @jaylikesbunda)
  - OFW: Heavily Expand Universal Remotes (by @jaylikesbunda)
- OFW: BadKB: Improve ChromeOS and GNOME demo scripts (by @kowalski7cc)
- OFW: GUI: Change dialog_ex text ownership model (by @skotopes)
- OFW: CCID: App changes and improvements (by @kidbomb)
- OFW: API: Exposed `view_dispatcher_get_event_loop` (by @CookiePLMonster)
- Furi:
  - UL: Extra checks for OTG power enable/disable (by @xMasterX)
  - OFW: Replace all calls to strncpy with strlcpy, use strdup more, expose strlcat (by @CookiePLMonster)
  - OFW: Threading, Timers improvements (by @CookiePLMonster)
  - OFW: FuriTimer uses an event instead of a volatile bool to wait for deletion (by @CookiePLMonster)
  - OFW: Improve FuriThread state callbacks (by @CookiePLMonster)
  - OFW: Increased heap size (by @hedger)
- Documentation:
  - OFW: Update and cleanup (by @rnadyrshin)
  - OFW: Improve bit_buffer.h docs (by @Astrrra)
  - OFW: Wi-Fi Devboard documentation rework (by @rnadyrshin)

### Fixed:
- RFID:
  - OFW: Fix detection of GProx II cards and false detection of other cards (by @Astrrra)
  - OFW: Fix Guard GProxII False Positive and 36-bit Parsing (by @zinongli)
  - OFW: GProxII Fix Writing and Rendering Conflict (by @zinongli)
- Desktop:
  - Fallback Poweroff prompt when power settings is unavailable (by @Willy-JL)
- Sub-GHz:
  - Fix GPS "Latitute" typo, switch to "Lat" and "Lon" in .sub files (#246 by @m7i-org)
  - UL: Fix zero issues in Princeton (by @xMasterX)
- Power: Suppress Shutdown on Idle While Charging / Plugged In (#244 by @luu176)
- Storage:
  - Fallback SD format prompt when storage settings is unavailable (by @Willy-JL)
  - OFW: Fix folder rename fails (by @portasynthinca3)
- About: Fix BLE stack version string (by @Willy-JL)
- OFW: Loader: Warn about missing SD card for main apps (by @Willy-JL)
- NFC:
  - UL: Read Ultralight block by block (by @mishamyte)
  - OFW: Fix crash on Ultralight unlock (by @Astrrra)
  - OFW: FeliCa anti-collision fix (by @RebornedBrain)
  - OFW: Emulation freeze fixed when pressing OK repeatedly (by @RebornedBrain)
- OFW: RPC: Broken file interaction fixes (by @RebornedBrain)
- OFW: GPIO: Fix USB-UART bridge exit screen stopping the bridge prematurely (by @portasynthinca3)
- OFW: GUI: Fix dialog_ex NULL ptr crash (by @Willy-JL)
- Furi:
  - OFW: Clean up of LFS traces (by @hedger)
  - OFW: Prevent idle priority threads from potentially starving the FreeRTOS idle task (by @CookiePLMonster)
  - OFW: Wait for RNG ready state and no errors before sampling (by @n1kolasM)
  - OFW: A Lot of Fixes (by @skotopes)
- OFW: CLI: Add warning about stealth mode in vibro command (by @ivanbarsukov)
- OFW: Debug: Use proper hook for handle_exit in flipperapps (by @skotopes)
- OFW: API: Fix kerel typo in documentation (by @EntranceJew)

### Removed:
- Apps:
  - Mifare Nested: Superseded by NFC app after OFW PR 3822 (MIFARE Classic Key Recovery Improvements)